Business Store is a dedicated, isolated, and private store for an enterprise. Enterprises can store various types of applications on this business store, and a holographic application is one of them.
Now, if you need to download any application from the Business Store, start the Store application within HoloLens. There, you will find a section for your organization; select that and you will find a list of applications hosted specific to your organization. Select application, download, and install.
You can visit the Microsoft Windows holographic application public store at https://www.microsoft.com/en-us/store/collections/hlgettingstarted/hololens.